The diminutive fighter, nicknamed " Ishak " or " Ishachok " " donkey " or "burro" by Soviet pilots, figured prominently in the Second Sino-Japanese War , [ 3 ] the Battle of Khalkhin Gol , [ 3 ] Winter War and the Spanish Civil War [ 4 ] [ 5 ] β where it was called the Rata " rat " by the Nationalists or Mosca " fly " by the Republicans. The Finns called the aircraft Siipiorava " flying squirrel ".
While working on the Polikarpov I biplane, Nikolai Nikolaevich Polikarpov began designing an advanced monoplane fighter. It featured cutting-edge innovations such as retractable landing gear and a fully enclosed cockpit, and was optimized for speed with a short stubby fuselage, and a Wright R radial engine in a NACA cowling.
The aircraft is small, light and simple to build. Full-scale work on the TsKB prototype began in June , and the aircraft was accepted into production on 22 November , a month before it took to the air.
The TsKB was of mixed construction, using a wooden monocoque fuselage and wings employing a KhMA chrome-molybdenum steel alloy wing spar, dural ribs and D1 aluminum alloy skinning on the center and leading edges, with the remaining portions of the wings fabric-covered. The cockpit was covered by a centimetre-wide 16 in canopy which featured an Aldis-type tubular gun sight which could slide back and forth on runners fitted with rubber bungee cords.
A L The main landing gear is fully retractable by a hand crank. The armament consisted of a pair of 7. These features were proposed at first by Andrei Tupolev ; however, the NII VVS Air Force Scientific Test Institute was more concerned about the stresses a typical combat aircraft was subjected to in combat, and initially considered the risk too great.
